According to the curve25519 paper a x25519 public key can be represented in 32 bytes.
The x25519 library I'm using (bouncycastle) however gives me a 33 byte representation according to this standard.
My 33 byte hex representation always begins with the hex 02 or 03.
How do I convert a 33 byte representation to a 32 byte representation?
And when I am provided with a 32 byte representation, how do I know whether to prepend 02 or 03 to it to convert it back to a 33 byte representation?